Fix some FileItemModal.svelte- locales strings

convert strings "Using Entire Document" and "Using Focused Retrieval"  to i18n locales,

to address issue: https://github.com/open-webui/open-webui/issues/15728

src/lib/components/common/FileItemModal.svelte

@@ -133,9 +133,9 @@
 							>
 								<div class="flex items-center gap-1.5 text-xs">
 									{#if enableFullContent}
-										Using Entire Document
+										$i18n.t('Using Entire Document')
 									{:else}
-										Using Focused Retrieval
+										$i18n.t(`Using Focused Retrieval')
 									{/if}
 									<Switch
 										bind:state={enableFullContent}